Sunday, January 07, 2007

Most of us have heard about the French Paradox, which basically says that the French eat masses of saturated fat and have a particularly low rate of heart disease. The usual explanation is that they are protected by all that red wine or their relaxed lifestyle or.... Unfortunately these do not protect the pasta based cuisine consumers of Italy. Quote "in contrast to the French Paradox, which examined how the indulgent French diet could produce favorable health outcomes, the studies of the Mediterranean diet has had the reverse effect in Italy". So do we now have a paradox within a paradox?

But then what about the

Spanish paradox Those naughty Spaniards are eating more fat and less carbs and getting LESS heart disease, now there's a suprise. Good job their medical system is so marvelous.

Sri Lanka paradox In Srilanka they eat <25% calories from fat and still get lots of heart disease. Tut tut.

Israeli paradox The Israelis eat buckets of polyunsaturated fat yet have a much higher heart attack rate than Europe.

Japanese paradox Not only are the naughty Japanese eating more fat, but it is RAISING THEIR SERUM CHOLESTEROL. GASP. So why is their heart attack rate dropping? Easy.

"a greater saturated fat intake is associated with less progression of coronary atherosclerosis, whereas carbohydrate intake is associated with a greater progression"

The basic puzzlement in all of these is that the more fat, particularly saturated fat, a nation consumes the LOWER its incidence of heart disease. Low fat consumption, or increased polyunsaturate consumption, INCREASES heart disease.

Of course all paradoxes resolve when you realise saturated fat is not the cause of heart disease....

Saturday, January 06, 2007

The Women's Health Initiative was a massive study of the benefits of reducing the percentage of dietary calories from fat. It involved 48,835 women, so not a small study. Remember that small effects require large studies to detect them. Big effects will show in small groups, so I don't like this study. However it involved a massive input of money to produce a snippet of interest. It also kept 47 authors in gainful employment for over eight years. The women in the intervention group achieved intakes of saturated fat and cholesterol that were less than 10% of energy intake and less than 300 mg/d, respectively. The question is, does reducing your fat intake by 8.2% provide any benefit on cardiovascular disease risk?

The answer is "No", not if you were free of heart disease to begin with. Summary:

There is no benefit. I mean

*******THERE IS NO BENEFIT********

NONE.

What if you are already suffering from heart disease? There was a small subgroup (1,656 women) who had cardiovascular disease at the start of the study. This is what happened to them, and I quote

"The intervention was associated with increased risk in the 3.4% of women with baseline CVD; this may be a chance observation, or rates in this small subset may be confounded by concurrent therapy or comorbid conditions"

The hazard ratio was 1.26 for this group. That is, there was a 26% increase in risk of a cardiovascular incident. You notice from the quote that this "may be a chance observation". I'll translate this for you. What the authors mean is:

They found that reducing the amount of fat in your diet INCREASES your risk of cardiovascular disease. They've tried every possible way of explaining this away and have COMPLETELY failed. If you have already got heart disease you must not reduce your fat intake, unless you really want increase your risk of another heart attack.

You could call this a paradox. I mean yet another paradox.

Or just accept that fat is not the cause of heart disease.

By the way, none of this made it in to the abstract, you must access the full text of the JAMA paper, where you have to trawl through the results to get the Hazard Ratio number.

About Me

I am Petro Dobromylskyj, always known as Peter. I'm a vet, trained at the RVC, London University. I was fortunate enough to intercalate a BSc degree in physiology in to my veterinary degree. I was even more fortunate to study under Patrick Wall at UCH, who set me on course to become a veterinary anaesthetist, mostly working on acute pain control. That led to the Certificate then Diploma in Veterinary Anaesthesia and enough publications to allow me to enter the European College of Veterinary Anaesthesia and Analgesia as a de facto founding member. Anaesthesia teaches you a lot. Basic science is combined with the occasional need to act rapidly. Wrong decisions can reward you with catastrophe in seconds. Thinking is mandatory.
I stumbled on to nutrition completely by accident. Once you have been taught to think, it's hard to stop. I think about lots of things. These are some of them.

Organisation (or lack of it)!

The "labels" function on this blog has been used to function as an index and I've tended to group similar subjects together by using labels starting with identical text. If they're numbered within a similar label, start with (1). The archive is predominantly to show the posts I've put up in the last month, if people want to keep track of recent goings on. I might change it to the previous week if I ever get to time to put up enough posts in a week to justify it. That seems to be the best I can do within the limits of this blogging software!